Browse Forums Eco Living Re: Another Rainwater Wet System Thread 2Feb 09, 2021 10:31 pm 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Another Rainwater Wet System Thread 4Feb 11, 2021 2:37 pm 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Another Rainwater Wet System Thread 5Feb 15, 2021 7:30 am "It must be remembered that gutter mesh promotes the accumulation of dirt which reconstitutes due to gutter mesh restricting the normally turbulent cross flushing from front to back during heavier rain." So if we can't fit leaf diverters, should we just forget the gutter mesh, too? Re: Another Rainwater Wet System Thread 6Feb 15, 2021 7:48 am SaveH20 I'm not but with 'some' reservation. Is the top of the riser above the tank? The 1:20 ARI figures are the minimum qualifying intensity, I always design for at least 20% more flow and even this is the bare bones although most gutters will overflow before this intensity is reached. A 22.5 degree roof is factored with a 1.21 multiplier allowing for wind driven rain when calculating eaves gutter 1:20 ARI compliance. If you calculate the flow from 60% of the roof with the 1.21 multiplier during a windy minimum qualifying 1:20 ARI (419 x 0.6 x 1.21 x 2.58 = 785 lpm), the required wet system flow rate with the available head is unobtainable. A ball park calculation to remember is that it requires x4 the head to double the flow rate. A saving grace is that not all of the 60% roof area will be facing the weather. With the assistance of the low restriction inlet this should be less of an issues the more empty the tank is. So it's really decent rainfall when the tank is already full or close to full isn't it. I am still concerned about this scenario though. Originally i had planned on having an extra 400mm head available however once the earthworks were completed for both house and tank this disappeared. There is one more option that has it's pros and cons of course, and that is to re-site the tank further downhill to achieve the required height differential. The tank has not been constructed yet however the pad has been cut and prepared, plus all of the pipework has been run to this location so there would be a decent cost. At this location the block falls at approx 1:18 so I could achieve an extra metre of head by moving it 18m further down the hill. This would mean an extra 18m of trenched pipework, power etc to the new location. Major issue there is that it would then fall into the area zoned as the "reserve" effluent management area. This is the secondary area designated for irrigation via the OSSM system. Not sure how flexible this is to be moved but will talk to the builders about that. So the big question is what is the ideal height differential from eaves to the top of the bellmouth overflow given all of the other system data stays the same but with a further ~20m of underground 2 x 100mm DWV piping? SaveH20 Unfortunately, I have never done any testing of these scenarios but my primary concern remains the capture and hold of 1-2 mm accumulated grit particles that are flushed from the gutters during heavy rain more so than a possible but not probable build up of small organic matter on mesh in a vertical pipe. It must be remembered that gutter mesh promotes the accumulation of dirt which reconstitutes due to gutter mesh restricting the normally turbulent cross flushing from front to back during heavier rain. If you have half round gutters that have superior flushing characteristics, I would say to give the Mozzie Stoppas a go but if you have quad guttering, I could not recommend it but the final decision is obviously yours. Maybe trial the 4 downpipes on the lesser roof area first. I understand what you are saying and agree it has the potential to require fairly regular maintenance. It's definitely quad guttering. I think I'm still half keen to give these a shot in the downpipes. Even if the tank gets moved as above it sounds like a relatively low cost option to trial and if they don't work then I can either just remove them or install a proper leaf diverter, pending on what height differential I manage to achieve. I did some very rough calcs based on the closest process I could find on the web to try and estimate what the pressure losses through the mesh screen may be and I came out at around 120mm head loss at a flow rate of 2L/s. Absolutely not exact science but means potentially could be less detrimental to the system flow than the head loss suffered from fitting leaf diverters. Certainly the aesthetic would be superior to the leaf diverters if nothing else. SaveH20 Fantastic! No drainage problems there. What is the distance between the bellmouth crest and the top of the tank? Still waiting for them to get back to me on this one... I asked the same question a week ago. SaveH20 Unfortunately yes. If you don't have possums or rats, maybe do away with the first flush and install a floating filter inlet instead...as well as the sediment trap ofc. Yep, thinking this is the way I will go. Especially since all tank water to the house will get filtered through one of these Water Filters also. SaveH20 I have seen the Scala2 advertised (from memory) for less than $700 which is incredible value for a VSD. Some people have trouble adjusting the pressure though but I believe this is due to not also adjusting the small pressure tank. There were also leakage problems with the earlier units but the problem was redesigned and all units sold were offered to be replaced. You use to be able to get a 4 year warranty but I don't know if that still applies. There is a guy on the Whirlpool Home forum who posts as paulvk, he seems to have good intimate knowledge about pumps. Maybe start a thread on there asking for a recommendation for a VSD pump. Thanks for the recommendation. I'll start dealing with the pump once I sort out the tank haha. Re: Another Rainwater Wet System Thread 7Feb 19, 2021 12:38 am therobbo With the assistance of the low restriction inlet this should be less of an issues the more empty the tank is. So it's really decent rainfall when the tank is already full or close to full isn't it. That is correct and a 50mm low restriction inlet is usually plenty big enough but I am thinking that a 65mm inlet would be better insurance in this situation. You can use a 100x65mm 45 degree DWV junction to branch the smaller pipe. You require a 20,000 litre fire fighting water reserve, I assume this requires a 65mm Storz outlet. Yes/No? Is there a set maximum height above the bottom of the tank that the valve cannot exceed? If the two 100mm pipes were kept separate, the pipe serving the smaller roof section would be ok but a 40mm inlet would still be beneficial in reducing the water retained in the downpipes and riser as well as having the benefit of oxygenating the heavier density water at the bottom of the tank. During a high intensity rain event, the sediment trap could also be used to great effect as an emergency discharge. One thing about modern technology is that everyone has access to the BOM radar which is a great tool. therobbo Originally i had planned on having an extra 400mm head available however once the earthworks were completed for both house and tank this disappeared. It was a good plan. therobbo There is one more option that has it's pros and cons of course, and that is to re-site the tank further downhill to achieve the required height differential. The tank has not been constructed yet however the pad has been cut and prepared, plus all of the pipework has been run to this location so there would be a decent cost. This also means more friction loss. I would leave it as is and possibly look at a quick fix at the house itself if necessary that could involve diverting excess water from the gutters to a smaller tank at the house or other measures already mentioned. The former could be done by utilising 50mm inverted nozzles to regulate the height of water in the gutter.. therobbo So the big question is what is the ideal height differential from eaves to the top of the bellmouth overflow given all of the other system data stays the same but with a further ~20m of underground 2 x 100mm DWV piping? Will the risers discharge above the tank's wall, i.e. will they be above the roof? Your question is extremely hard to calculate because the downpipes have friction losses through the tees yet they also exert positive pressure at different intervals on flowing water that has already been subjected to friction losses plus the flow through the low restriction inlets will vary with their size and the tank's varying water level. I think that the tank can stay where it is and that a low 65mm valve is all that is required but a 50mm valve would work while there was mitigation (providing additional head) in the tank which of course could not be relied on. I am in the process of designing an expo display using clear pvc pipe and fittings that will include a demonstration of two gravity fed water columns (think downpipes) spaced apart with other water columns spaced along the flow path to show the increasing loss of pressure along the carrier pipe and the flow and pressure influence when the second water column is activated on demand. The video below demonstrates a carrier pipe's increasing friction losses along its length, just visualise gravity feeding two spaced apart water columns with the pressure indicator water columns in between plus one fitted after the second gravity fed column. https://www.youtube.com/watch?v=_hSL9_eo4n8&t=96s therobbo I think I'm still half keen to give these a shot in the downpipes. Even if the tank gets moved as above it sounds like a relatively low cost option to trial and if they don't work then I can either just remove them or..... I have been thinking about this quite a bit and it is a hard one. If someone asked me if it was a good idea to put fine mesh at the top of a downpipe, I would immediately say no and the same concerns applies to mesh being fitted in the downpipe. Contrary to this however is that they are easily accessible for cleaning and you can also get oversized ones. I haven't priced the larger ones yet. The bottom line of course is that water must pass through mosquito proof mesh prior to entering a tank and you need to have low restriction inlets. I can't say "Yes, give it a go" because there is the possibility of it not working to advantage during a sudden downpour and I don't want to be the one who stood by and encouraged it. You have a very good knowledge of best practice and awareness of critical flow design and so I think that you are safe in making decisions because I know that you will be on top of a situation if one did arise and you will have formulated an action plan. If the tank is less than 3/4 full, there won't be a problem. I would be very interested to know how you go with your plan. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Another Rainwater Wet System Thread 8Feb 19, 2021 9:25 am SaveH20 A 50mm inlet is usually plenty big enough but I am thinking that a 65mm inlet would be better insurance in this situation. You could use a 100x65mm 45 degree junction to branch the smaller pipe. Sounds reasonable, I'll see if I can make that change to the tank. They will be getting sick of me changing my options by now. SaveH20 You require a 20,000 litre fire fighting water reserve, I assume this requires a 65mm Storz outlet. Yes/No? Is there a set maximum height above the bottom of the tank that the valve cannot exceed? Yes, correct. The reserve level will be ~500mm up the tank wall, this is where the pump outlet will be located. The tank salesman was convinced that I could not fit inlet valves within this reserve area of the tank so the extra inlets were optioned at the pump takeoff height also. However I phoned the local RFS and they advised as long as they were only inlets that they did not have an issue wherever they were fitted so I will be getting them positioned 150mm above tank base. SaveH20 If the two 100mm pipes were kept separate, the pipe serving the smaller roof section would be ok but a 40mm inlet would still be beneficial in reducing the water retained in the downpipes and riser as well as having the benefit of oxygenating the heavier density water at the bottom of the tank I'm thinking of branching the two 100mm pipes together to help balance flows between the two roof sections and reduce frictional losses due to excessive flow rates. I was only planning on having a single low inlet for the 2 x 100mm pipes from the house and a second one to service the shed stormwater. As you mention above it may be best to make the house inlet a 65mm valve. SaveH20 This also means more friction loss. I would leave it as is and possibly look at a quick fix at the house itself if necessary that could involve diverting excess water from the gutters to a smaller tank at the house or other measures already mentioned. The former could be done by utilising 50mm inverted nozzles to regulate the height of water in the gutter.. This sounds like more surface run pipes to me, as well as an extra tank near the house? Definitely something I'm trying to avoid to be able to get the balance between function and aesthetics. If I connected the 2 x 100mm pipes to a single 150mm pipe run for the extra distance then frictional losses would be minimised. It would mainly be the extra fittings contributing. An 18m length of 150NB pipe flowing at 1081lpm would contribute ~100mmH2O in pressure losses. So effectively I could achieve an extra 1000mm head while sacrificing potentially 2-300mm extra frictional losses. It will cost a bit more upfront but I'm thinking more and more that it may be worth it to save potential long term pain. SaveH20 Will the riser discharge above the tank's walls i.e. will it be above the roof? Yes it will be above the tank wall height. So height from base of tank to discharge centreline would probably be ~2.3m. This would place it ~400mm below the eaves, something I get more concerned about everytime I think about it. SaveH20 The bottom line of course is that water must pass through mosquito proof mesh prior to entering a tank and you need to have low restriction inlets. I can't say "Yes, give it a go" because there is the possibility of it not working to advantage during a sudden downpour and I don't want to be the one who stood by and encouraged it. Yep this i where the problem keeps coming back to haha. Even if I was happy enough for the gutters to overflow during heavier rain events when the water tank is already reasonably full, I still need to find a workable solution to exclude mozzies. If I leave the tank in it's currently planned location then I can't see that I have any other option but to use the retractable mozzie stoppa style mesh at the downpipes to screen for insects. If they were to be an epic failure due to restriction of flow and buildup of material, which there is every chance they could be haha, then I'm leaving myself with no simple fix aren't I? If I can increase the height differential then at least I have the option to fit traditional leaf diverters if these were to be a failure. Also speaking of overflowing, in your experience have you been able to identify a rule of thumb style guide to what sort of rain inflows standard quad guttering can handle before they overflow, regardless of the resistance in the downpipes and stormwater system? I imagine this is a possibility as a 115mm gutter cant transfer an infinite amount of water. Would be a good rough figure to have, although I'm sure near impossible to get, as then we would know a ceiling limit to design to. Thanks again for all your help SaveH2O. Re: Another Rainwater Wet System Thread 9Feb 24, 2021 1:54 am therobbo SaveH20 A 50mm inlet is usually plenty big enough but I am thinking that a 65mm inlet would be better insurance in this situation. You could use a 100x65mm 45 degree junction to branch the smaller pipe. Sounds reasonable, I'll see if I can make that change to the tank. They will be getting sick of me changing my options by now. But can't you use the 65mm Storz inlet if the inlet line can be easily uncoupled? Your firefighting reserve usually requires a 65mm Storz valve. therobbo The tank salesman was convinced that I could not fit inlet valves within this reserve area of the tank so the extra inlets were optioned at the pump takeoff height also. However I phoned the local RFS and they advised as long as they were only inlets that they did not have an issue wherever they were fitted so I will be getting them positioned 150mm above tank base. The salesman is wrong, he obviously couldn't get his head around a valve being used as an inlet and not exclusively as an outlet. That is funny. therobb0 I'm thinking of branching the two 100mm pipes together to help balance flows between the two roof sections and reduce frictional losses due to excessive flow rates. If they run parallel, could you merge them to a 150mm pipe? therobbo This sounds like more surface run pipes to me, as well as an extra tank near the house? Definitely something I'm trying to avoid to be able to get the balance between function and aesthetics. I agree. It isn't something to consider now because there are workable options, just something that 'could' be considered later if for some reason the better options were overwhelmed. You can also use a sediment trap as an emergency relief outlet during a high intensity rain event. therobbo If I leave the tank in it's currently planned location then I can't see that I have any other option but to use the retractable mozzie stoppa style mesh at the downpipes to screen for insects. If they were to be an epic failure due to restriction of flow and buildup of material, which there is every chance they could be haha, then I'm leaving myself with no simple fix aren't I? If I can increase the height differential then at least I have the option to fit traditional leaf diverters if these were to be a failure. There is a larger Mozzie Stoppa Advanced Max Flow that can be plumbed into a 90mm downpipe. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ https://youtu.be/bG-0UdnTkNQ https://youtu.be/R_L9rqBIZCU https://www.youtube.com/watch?v=8U9T1avFULY&feature=emb_rel_end I haven't been able to find a price for the bigger one plus couplings or even find them for sale. It would try this but have a spare screen to save having to get up and down the ladder more than once. Re restriction of flow caused by the mesh itself...Water passing through mesh at the top of the downpipe is not a consideration if considering possible friction loss but having six 90mm downpipes discharging into a 100mm carrier pipe is. I haven't been able to find any references to friction loss for DWV 88 degree tee junctions. There is a slight curve at the branch and so the friction loss through the run isn't the same as 'square' tees as used in the various flow loss tables. The tee however reduces the downpipe's effectiveness as a 'booster pump'. Sometime down the track I will set up a test using either 40mm or 50mm DWV fittings and conduct tests for pressure and flow rate changes at varying tee and 45 degree wye junction intervals. I have not been able to find any experiments done with spaced downpipes and this surprises me, everyone uses just the one head source. Low inlets assist flow and I have often seen them successfully stop leaf diverters overflowing during heavy rain but the additional head gained between the tank's water level (above the bellmouth's crest) when full and half way above the riser's discharge invert is still unknown. With there now being only 400mm between the riser and the gutter's sole, I am not 100% confident of the wet system draining six downpipes once the tank fills during a storm without knowing the air gap height above the bell mouth. You need to factor a flow of at least 700 lpm as a bare minimum to allow for even minimal wind driven rain. There are a number of flow calculators online, the one below is simple to use. https://www.omnicalculator.com/physics/pipe-flow therobbo Also speaking of overflowing, in your experience have you been able to identify a rule of thumb style guide to what sort of rain inflows standard quad guttering can handle before they overflow, regardless of the resistance in the downpipes and stormwater system? I imagine this is a possibility as a 115mm gutter cant transfer an infinite amount of water. Would be a good rough figure to have, although I'm sure near impossible to get, as then we would know a ceiling limit to design to. A gutter's flow rate depends a lot on slope, length and preferably not having internal gutter clips. The link below will assist but note that I would never recommend having a minimal 1:500 gutter slope on which the figures are based. https://www.acegutters.com.au/technical ... -flow-rate 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Hi, Apologies - I know there is plenty out there on this but struggling to put together the puzzle. We're planning our garage/external laundry to master bedroom and… 0 11117 Once you know the basics, the rest is easy. Read my post in the thread linked below. viewtopic.php?p=1919271#p1919271 2 19515 18 90480 |